Bayesian Restoration of Single-Channel Patch Clamp Recordings

Biometrics ◽  
1992 ◽  
Vol 48 (2) ◽  
pp. 427 ◽  
Author(s):  
Donald R. Fredkin ◽  
John A. Rice
Keyword(s):  
Patch Clamp ◽  
Single Channel ◽  
Bayesian Restoration

Ionic channels in corneal endothelium

1996 ◽  
Vol 270 (4) ◽  
pp. C975-C989 ◽  
Author(s):  
J. L. Rae ◽  
M. A. Watsky
Keyword(s):  
Patch Clamp ◽  
Corneal Endothelium ◽  
Single Channel ◽  
Cell Voltage ◽  
Anion Channel ◽  
Ionic Channels ◽  
K Channel ◽  
Na Channel ◽  
Channel Blockers ◽  
K Currents

Single-channel patch-clamp techniques as well as standard and perforated-patch whole cell voltage-clamp techniques have been applied to the study of ionic channels in the corneal endothelium of several species. These studies have revealed two major K+ currents. One is due to an anion- and temperature-stimulated channel that is blocked by Cs+ but not by most other K+ channel blockers, and the other is similar to the family of A-currents found in excitable cells. The A-current is transient after a depolarizing voltage step and is blocked by both 4-aminopyridine and quinidine. These two currents are probably responsible for setting the -50 to -60 mV resting voltage reported for these cells. A Ca(2+)-activated ATP-inhibited nonselective cation channel and a tetrodotoxin-blocked Na+ channel are possible Na+ inflow pathways, but, given their gating properties, it is not certain that either channel works under physiological conditions. A large-conductance anion channel has also been identified by single-channel patch-clamp techniques. Single corneal endothelial cells have input resistances of 5-10 G omega and have steady-state K+ currents that are approximately 10 pA at the resting voltage. Pairs or monolayers of cells are electrically coupled and dye coupled through gap junctions.

Persistence: a new statistic for characterizing ion-channel activity

1995 ◽  
Vol 350 (1334) ◽  
pp. 353-367 ◽  
Keyword(s):  
Patch Clamp ◽  
Ion Channel ◽  
Single Channel ◽  
Statistical Technique ◽  
Channel Activity ◽  
Patch Clamp Recording ◽  
Conductance Level

We introduce and illustrate by examples a new statistical technique, the persistence function, for characterizing ion-channel activity in a single-channel patch-clamp recording. Persistence is a function of both current and time. It is the probability that the current is at a given level (conditional on it having been at that level at an earlier time). Viewed as a function of current it exhibits the prominent conductance levels present in the recording, and viewed as a function of time for a conductance level it portrays the kinetics at that level.

scholarly journals The Tyrosine Kinase p56lck Mediates Activation of Swelling-induced Chloride Channels in Lymphocytes

1998 ◽  
Vol 141 (1) ◽  
pp. 281-286 ◽  
Author(s):  
Albrecht Lepple-Wienhues ◽  
Ildikò Szabò ◽  
Tilmann Laun ◽  
Nubia Kristen Kaba ◽  
Erich Gulbins ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Tyrosine Kinase ◽  
Single Channel ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Osmotic Swelling ◽  
Whole Cell ◽  
Herbimycin A ◽  
Unitary Conductance ◽  
Human T Cell

Osmotic cell swelling activates Cl− channels to achieve anion efflux. In this study, we find that both the tyrosine kinase inhibitor herbimycin A and genetic knockout of p56lck, a src-like tyrosine kinase, block regulatory volume decrease (RVD) in a human T cell line. Activation of a swelling-activated chloride current (ICl−swell) by osmotic swelling in whole-cell patch-clamp experiments is blocked by herbimycin A and lavendustin. Osmotic activation of ICl−swell is defective in p56lck-deficient cells. Retransfection of p56lck restores osmotic current activation. Furthermore, tyrosine kinase activity is sufficient for activation of ICl−swell. Addition of purified p56lck to excised patches activates an outwardly rectifying chloride channel with 31 pS unitary conductance. Purified p56lck washed into the cytoplasm activates ICl−swell in native and p56lck-deficient cells even when hypotonic intracellular solutions lead to cell shrinkage. When whole-cell currents are activated either by swelling or by p56lck, slow single-channel gating events can be observed revealing a unitary conductance of 25–28 pS. In accordance with our patch-clamp data, osmotic swelling increases activity of immunoprecipitated p56lck. We conclude that osmotic swelling activates ICl−swell in lymphocytes via the tyrosine kinase p56lck.

scholarly journals Basolateral P2X4 channels stimulate ENaC activity in Xenopus cortical collecting duct A6 cells

2014 ◽  
Vol 307 (7) ◽  
pp. F806-F813 ◽  
Author(s):  
Tiffany L. Thai ◽  
Ling Yu ◽  
Douglas C. Eaton ◽  
Billie Jean Duke ◽  
Otor Al-Khalili ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Single Channel ◽  
Collecting Duct ◽  
Reversal Potential ◽  
Receptor Activation ◽  
Dominant Negative ◽  
Phosphatidylinositol 3 Kinase ◽  
A6 Cells ◽  
Basolateral Side ◽  
Phosphatidylinositol 3

The polarized nature of epithelial cells allows for different responses to luminal or serosal stimuli. In kidney tubules, ATP is produced luminally in response to changes in luminal flow. Luminal increases in ATP have been previously shown to inhibit the renal epithelial Na+ channel (ENaC). On the other hand, ATP is increased basolaterally in renal epithelia in response to aldosterone. We tested the hypothesis that basolateral ATP can stimulate ENaC function through activation of the P2X4 receptor/channel. Using single channel cell-attached patch-clamp techniques, we demonstrated the existence of a basolaterally expressed channel stimulated by the P2X4 agonist 2-methylthio-ATP (meSATP) in Xenopus A6 cells, a renal collecting duct principal cell line. This channel had a similar reversal potential and conductance to that of P2X4 channels. Cell surface biotinylation of the basolateral side of these cells confirmed the basolateral presence of the P2X4 receptor. Basolateral addition of meSATP enhanced the activity of ENaC in single channel patch-clamp experiments, an effect that was absent in cells transfected with a dominant negative P2X4 receptor construct, indicating that activation of P2X4 channels stimulates ENaC activity in these cells. The effect of meSATP on ENaC activity was reduced after chelation of basolateral Ca2+ with EGTA or inhibition of phosphatidylinositol 3-kinase with LY-294002. Overall, our results show that ENaC is stimulated by P2X4 receptor activation and that the stimulation is dependent on increases in intracellular Ca2+ and phosphatidylinositol 3-kinase activation.

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